Study On Gemmological Characteristics Of A Kind Of Quartzose Jade Called "Jinmai" Stone

"Jinmai stone"is a kind of silica jade from the gobi desert of China and Mongolia border.It has a variety of colors,including red,yellow,green,gray and purple,etc.It has a variable appearance and can develop ridges like"sinew".Or develop mammary projections,such as"fish roe";Can also develop yellow core and colorless shell,like"sun egg";Concentric ring structures,such as"eyes",can also be developed.The"tendons"are the most representative.Samples are collected from Erenhot,Inner Mongolia.In this paper,hand specimen observation,conventional gemological testing,rock ore partial reflective microscope,scanning electron microscope?SEM?,electron probe and transmission infrared spectroscopy,X-ray powder diffraction and Raman spectra and other modern testing technology are used to make gemological research on"Jinmai stone".The main structures include cryptocrystalline structure,idiomorphic granular structure,cryptocrystalline fibrous structure and its derivative structure.In"veins"?also called“Jinmai”?,cryptocrystalline structure,parallel fiber structure and interwoven short fiber structure were more common,while in"meat"?also called“rou”?,cryptocrystalline structure and crystalloid comb structure were more common?sphere-granular micromorphology?."Fish roe"is fibrous columnar structure,"sun egg"agate always have fiber radial structure.Under scanning electron microscope,the structural growth sequence of"Jinmai stone"can be obtained according to the particle size relationship.The particle size increases and the maturity increases along the sequence of fibriform,lamellar,pellet-rhombohedral,radial and hexagonal rhombohedral,and the particles with larger particle size can be developed from those with smaller particle size.The ratio of absorption peak strength at 501cm^-11 and 464cm^-1 in the Raman spectroscopy test was used to calculate the content of moganite."tendons"were higher than"meat".The structural growth sequence could be obtained according to the arrangement of particle size from small to large,and the content of moganite decreased along this sequence:Fiber radial?<30nm?has the content from 55%-72%,layered structure?<100nm?contents 35%-65%,sphaerulitic structure?0.5-4um?owns 0%-38%.There is no moganite in the rhombohedral structure?3-10um?,fibrous column?200-400um?,and hexagonal column/rhombohedral structure?0.5-1mm?.X-ray powder crystal diffraction and infrared spectrum showed that"Jinmai stone"is a mixture of?-quartz and moganite.In X-ray powder crystal diffraction,diffraction peaks at d=4.43,4.35,3.11 and 2.88 and absorption peaks at ir spectra of 555 and 615cm^-1indicated the presence of moganite.Compared with"meat","tendons"have more obvious characteristic peaks of moganite.The crystallinity of the"tendons"and"meat"of the"Jinmai stone"was tested,and it was concluded that the crystallinity of the"tendons"was much less than that of the"meat".The crystallinity of the"tendons"part CI_J=0.43,and that of the"meat"part CI_R=9.17 by the five-finger peak test of X-ray powder diffraction.The crystallinity of"tendons"of“Jinmai stone”shows K=2.15,and"meat"part K=3.07 were obtained by characteristic peak near 800cm-1.Moganite usually indicates the alkaline iron-rich silicon supersaturated solution under evaporation environment,and the growth of"Jinmai"conforms to the fractal theory.Pyrite chlorite and calcite can be crystallized in the later reduction environment.